The evolution of the third generation (3G) air interface technologies, such as downlink multiple input multiple output (MIMO), downlink 64 quadrature amplitude modulation (QAM), and uplink 16QAM, significantly improves the transmission rate of the air interface, and doubles the throughput of the packet switching (PS) service. As a result, service general packet radio service support nodes (SGSNs), gateway general packet radio service support nodes (GGSNs), value added services (VASs), and the transmission bearers among these nodes encounter an unprecedented pressure, and particularly, rich Internet services raise higher requirements for the transmission bandwidth of the core network (CN), causing that the cost of capacity expansion increases rapidly. The Internet services occupy a large number of transmission resources of mobile operation networks but bring lower profits for mobile operators, and in addition, when users access the Internet services of the packet data network (PDN), the packet flow passes through numerous nodes of the core network, and transmission efficiency is quite low. Therefore, currently the operators are eager to seek a suitable solution, where the nodes near the access side directly route the uplink Internet service flow to the PDN network at low cost, and on contrary, the downlink traffic flow is also directly routed from the PDN network to the access side, so as to offload the data flow of the core network.
In the prior art, that a traffic offload function (TOF) entity for offloading a user data flow is added between a radio network controller (RNC) and an SGSN is proposed, where the TOF entity may be deployed on an Iu-PS interface between a universal mobile telecommunication system (UMTS) network RNC or home Node B gateway (HNB GW) and the SGSN. The TOF entity provides a standard Iu interface towards the RNC/HNB GW and towards the SGSN, and completes the traffic offload function through the Gi interface.
However, the prior art only supports the continuity of offloaded traffic of a mobile user equipment (UE) under a same TOF entity, but does not support the continuity of offloaded traffic of a mobile UE across different TOF entities. Furthermore, in some scenarios, the prior art has problems, for example, the TOF entity is unable to obtain user information.